Dengue: Infection and Treatment by Mahmoud Lubbad

Alternative Names Onyong- Nyang Fever West Nile Fever Break Bone Fever Dengue like Disease

Dengue The word dengue is derived from African word denga: meaning fever with hemorrhage . Is caused by virus transmitted of bites of mosquito Aedes.

History The first outbreak that resembles a disease now recognized as dengue fever was that described by Benjamn Rush in Philadelphia, Pennsylvania in 1780.

Problem statement Dengue fever is the most common arthropod borne viral disease. Dengue fever is one of the most important emerging disease of the tropical and sub tropical regions, affecting urban and pre urban areas.

Virus 2

Group A Togaviruses e.g. encephalitis Group B Togaviruses Sandfly fever Rift valley fever Cramean –Congo fever By Mosquito Yellow fever, Denque fever By Ticks Russian fever E. Spring Summer fever

The Dengue Virus Four types :Has 4 serotypes (DEN-1, 2, 3, 4) Causes dengue and dengue hemorrhagic fever Is an arbovirus Transmitted by mosquitoes Composed of single-stranded RNA

Dengue Viruses Each serotype provides specific lifetime immunity, and short-term cross-immunity All serotypes can cause severe and fatal disease Genetic variation within serotypes Some genetic variants within each serotype appear to be more virulent or have greater epidemic potential 4

Dengue Symptoms Undifferentiated fever Classic dengue fever Dengue hemorrhagic fever Dengue shock syndrome 17

Undifferentiated Fever May be the most common manifestation of dengue Prospective study found that 87% of students infected were either asymptomatic or only mildly symptomatic Other prospective studies including all age- groups also demonstrate silent transmission DS Burke, et al. A prospective study of dengue infections in Bangkok. Am J Trop Med Hyg 1988; 38:172-80.

Clinical Characteristics of Dengue Fever Headache Muscle and joint pain Nausea/vomiting Rash Hemorrhagic manifestations 18

Hemorrhagic Manifestations of Dengue Skin hemorrhages: نزيف الجلد petechiae, purpura, ecchymoses Gingival bleeding نزيف للثة Nasal bleeding نزيف للأنف Gastro-intestinal bleeding: نزيف للأمعاء hematemesis, melena, Hematuria Increased menstrual flow زيادة تدفق الطمث 20

Skin bleeds

Bleeding into the eye

Large bleed into skin

Clinical Case Definition for Dengue Shock Syndrome Evidence of circulatory failure manifested indirectly by all of the following: Rapid and weak pulse Narrow pulse pressure ( 20 mm Hg) OR hypotension for age Cold, clammy skin and altered mental status Frank shock is direct evidence of circulatory failure 22

Aedes Aegypti Mosquito 8

3-14 days (commonly 4-7 days) Incubation period 3-14 days (commonly 4-7 days)

Aedes Aegypti Dengue transmitted by infected female mosquito Highly domesticated tropical mosquito. Prefer to lay eggs in artificial containers e.g. flower vases, automobile tires…etc. Prefer to rest indoors. Prefer to feed on humans during daytime hours. 9

Vector Aedes mosquitoes (Tiger mosquito): distinguished by white stripes on black body. Important members Aedes family: Aedes . Aegypty, Aedes.vittatus and Aedes. albopictus. They are most abundant during rainy season.

Vector Lays egg singly, and eggs are cigar shaped. Female mosquito acts as vector. They do not fly over long distance- <100mts(110yards), this factor facilitates its eradication.

World Distribution of Dengue 1999 Areas infested with Aedes aegypti Areas with Aedes aegypti and recent epidemic dengue

Dengue fever in KSA Year N. of suspected cases N. of confirmed cases 1994 1995 1996 1997 1998 1999 2000 2001 2002 673 136 57 62 31 26 17 07 11 289 6 2 15 00 3 4 Total 1020 319

Rift Valley Fever cases Dengue Fever cases Year-wise   289 1994 6 1995 2 1996 15 1997 1998 3 1999 1328 2000 2001 4 2002 2003 2004 406 2005 1544 2006 490 2007 913 2008 3350 2009 3526 2010 2011

Vector and Transmission

Replication and Transmission of Dengue Virus (Part 1) 1. Virus transmitted to human in mosquito saliva 2 2. Virus replicates in target organs 4 3 3. Virus infects white blood cells and lymphatic tissues 4. Virus released and circulates in blood 6

Replication and Transmission of Dengue Virus (Part 2) 6 5. Second mosquito ingests virus with blood 6. Virus replicates in mosquito midgut and other organs, infects salivary glands 7 5 7. Virus replicates in salivary glands 7

Pathogenesis In experimental studies of dengue virus infection in rhesus monkeys, after subcutaneous inoculation, virus was disseminated rapidly to regional lymph nodes and then to lymphatic tissue through out the body.

What are the tests needed? Routine blood test Tests to check the clotting process Special tests to identify the Dengue or its foot marks in our blood Urine to check protein leak

Special Test (ELISA) ELISA Plate IgM-capture ELISA

Treatment of Dengue Supportive measures – Mosquito screen Avoid Aspirin . Plenty of water and salt are required Children below 12 require careful watch for dangerous form No antibiotics are of proven value

Prevention

Mosquito Control How to prevent mosquito spread? Frequently (once in 2-3 days) empty all water storage containers Cover your over tanks to prevent mosquitoes breeding in fresh water Do not allow empty vessels, coconut shells, plastic containers, flower pots, tires etc to collect rain water in them

How to prevent mosquito bites? Screen your homes with mosquito screens like Netlon . Wear full clothing – long sleeves. Apply mosquito repellents like Odomos. Keep Dengue fever patient under mosquito net. True community participation is key.           

Thank you